Trimethylsilyl trifluoromethanesulfonate TMSOTf

A diastereoselective synthesis of /3-(iV-acylamino)aldehydes was accomplished via ruthenium-catalyzed isomerization of 0-vinyl-iV,0-acetals followed by rearrangement in the presence of trimethylsilyl trifluoromethanesulfonate (TMSOTf) (Scheme 36).63... 

CAUTION Many organotin compounds are known to be highly toxic 2 (Note 1), and hydrogen bromide (HBr), titanium tetrachloride (TiCi4), and trimethylsilyl trifluoromethanesulfonate (TMSOTf) are corrosive. Steps A-C should be performed in an efficient fume hood while wearing gloves and adequate eye protection. 

A typical coupling cycle (Scheme 2) for glycosyl trich1oroacet.imidat.es is outlined in Table I. A polystyrene support, functionalized with an olefinic linker, is loaded into a reaction vessel in the instrument.1617 The activating reagent (trimethylsilyl trifluoromethanesulfonate (TMSOTf /... 

The 4,7-dimethoxy-2,2-dimethyl-l,3,2-benzodiselenastannole 321 was prepared from commercially available 1,4-dimethoxybenzene 320 by a sequence of tandem ortho-lithiation and selenation, and followed by dimethyltin protection in 28% yield (Scheme 51). Then, sequential treatment of the stannole 321 in THF with selenyl chloride, trimethylsilyl trifluoromethanesulfonate (TMSOTf), and samarium iodide gave crystalline 4,7-dimethoxybenzotri-selenole 42 in 75% yield <1996H(43)1843>. The structure was characterized by X-ray crystallographic analysis (Section 6.12.3.1). 

Add slowly trimethylsilyl trifluoromethanesulfonate (TMSOTf) (0.1 eq) and stir reaction mixture at — 15°C for 1 h and at room temperature overnight (see Note 11). 

Reaction of benzaldehyde and its 4-nitro derivative with the enantiopure diene 796 in DCM and in presence of trimethylsilyl trifluoromethanesulfonate (TMSOTf) afforded the condensed enantiopure oxathiocanes 777 and 778 (50% yield). The reaction path began with the ionic addition of the diene 796 onto the carbon atom of the aldehyde function in 797a,b activated by trimethylsilyl cation attack to the carbonyl oxygen. 

After the readily available Friedel-Crafts catalyst, tin(IV) chloride, had been established as a catalyst for nucleoside synthesis, several other new catalysts, such as trimethylsilyl triflate (trimethylsilyl trifluoromethanesulfonate TMSOTf), etc., which are less acidic as Lewis acids... 

Human-glucose-dependent insulinotropic polypeptide (human GIP) was synthesized by the route shown in Scheme Trimethylsilyl trifluoromethanesulfonate (TMSOTf) has also... 

Toshima, K, Ishizuka, T, Matsuo, G, Nakata, M, Allyl C-glycosidations of totally unprotected glycals and allyltrimethylsilane with trimethylsilyl trifluoromethanesulfonate (TMSOTf), Tetrahedron Lett., 35, 5673-5676, 1994. 

R. Noyori developed a procedure that avoids migration of the double bond during acetalization of a, 3-unsaturated ketones (enones)A Treatment of the enone with the silylated diol l,2-bis[(trimethylsilyl)oxy]ethane in the presence of a catalytic amount of trimethylsilyl trifluoromethanesulfonate (TMSOTf ) affords the acetal without double bond migration (kinetic control). The stability of the Me3Si-0-SiMe3 formed (instead of HjO) drives the reaction to completion. Modifications of Noyori s procedure in which preparation of the silylated diol is circumvented have been reported. ... 

Recent improvements in the standard synthetic procedure using haloacetates have featured the use of trialkyi phosphites and activated acetates in the presence of trimethylsilyl trifluoromethanesulfonate (TMSOTf) as activating reagent. " This reaction has proved to be of great value in constructing complex sugar phosphonates. For example, in the presence of TMSOTf, the Michaelis-Arbuzov reaction between protected ketose acetates and triethyl phosphite takes place in ( 1 FC F at room temperature to produce, after deprotection, the expected diethyl l-(methoxycarbonyl)alkyl-phosphonates in high yields. -" ... 

Aldol-type condensation of enol silyl ethers and acetals or orthoesters can be accontplished by the use of trimethylsilyl trifluoromethanesulfonate (TMSOTf). In these reactions, TMSOTf acts as a true catalyst and is required in 1-S ntol %. The reactions show interesting chemoselectivity in that acetals are highly reactive receptors of enol silyl ethers but the parent aldehydes and ketones do not react under these conditions (Scheme 37). Similarly, trityl perchlorate is found to be an efficient catalyst to promote the reaction between enol silyl ethers and acetals. 

A bifunctional allylsilane reagent has been developed in which an initial nucleophilic attack at an acetal centre, mediated by trimethylsilyl trifluoromethanesulfonate(TMSOTf). is followed by cyclization of the allylsilane portion onto an electrophilic site, mediated by titanium(IV) chloride11. 

Another factor, which can eliminate the effect of remote acyl groups, is the choice of a promoter. Thus, trimethylsilyl trifluoromethanesulfonate (TMSOTf)-promoted... 

When 2,3-epoxy amine 5, structurally related to epoxyalkanes 1 and 2 was treated with trimethylsilyl trifluoromethanesulfonate (TMSOTf) in CDCI3 at - 40°C, and the reaction mixture was allowed to warm to room temperature, the H-NMR spectrum of the resulting solution clearly showed the formation of a new compound 6, stable at room temperature (Scheme 6.2). Compound 6 was very reactive in the presence of nucleophiles yielding, after hydrolysis, products with the structure of aminoalcohols. 

Kaw cki used optically active sulfonamide 234 to perform an asymmetric aza-Diels-Alder reaction with Rawal diene 235. " The reaction was performed in the presence of a Lewis acid, trimethylsilyl trifluoromethanesulfonate (TMSOTf), to obtain dihydropyridinone 236 as the product with high enantiomeric excess (Scheme 40.51). 

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